Abrasive tool and methods of producing same

ABSTRACT

An abrasive wire brush tool is provided with an embedded mass which surrounds the bases of the brush bristles of the abrasive tool, but leaves free ends of the brush bristles to which abrasive grains are bonded. The tool is well suited for polishing operations or for aftergrinding operations on manually manipulated workpieces of complex shape, especially plastic or wood workpieces.

United States Patent [1 1 Enzian [451 May 27, 1975 ABRASIVE TOOL AND METHODS OF PRODUCING SAME [75] Inventor:

[73] Assignee: The Carborundum Company,

Niagara Falls, NY.

22 Filed: Feb. 19, 1974 21 Appl. No.1 443,538

Edwin Enzian, Munden, Germany [30] Foreign Application Priority Data Feb. 20, 1973 Germany 2308258 [52] US. Cl 51/206 R; 51/298; 51/394 [51] Int. Cl..... B24b 5/00; 1324b 11/00; C08g 51/12 [58] Field of Search 51/330, 206 R, 293-298,

[56] References Cited UNITED STATES PATENTS 8/1952 Fromson 51/341 10/1963 Peterson 51/206 R 3/1964 Peterson 51/206 R 3,142,081 7/1964 Hartz et a1. 15/179 3,233,271 2/1966 Charvat 15/179 3,384,915 5/1968 Rands 15/179 3,529,945 9/1970 Charvat 51/295 3,577,839 5/1971 Charvat et a1. 15/179 FOREIGN PATENTS OR APPLICATIONS 1,006,829 4/1957 Germany Primary Examiner-Othell M. Simpson Attorney, Agent, or Firm-David E. Dougherty; Raymond W. Green [57] ABSTRACT An abrasive wire brush tool is provided with an embedded mass which surrounds the bases of the brush bristles of the abrasive tool, but leaves free ends of the brush bristles to which abrasive grains are bonded. The tool is well suited for polishing operations or for aftergrinding operations on manually manipulated workpieces of complex shape, especially plastic or wood workpieces.

20 Claims, 4 Drawing Figures ABRASIVE TOOL AND METHODS OF PRODUCING SAME BACKGROUND OF THE INVENTION This invention relates to an abrasive brush tool and methods for producing such an abrasive brush tool. In particular, this invention relates to an abrasive brush tool of high sharpness and of a high dimensional accuracy and of a high resistance to clogging by abraded material, as well as to different methods for the production of such an abrasive tool.

Wood, plastic and various metallic materials are difficult to machine with solid grinding wheels, because of clogging. The use of coated abrasive belts brings about difficulties in some situations, in particular in those cases where a high abrasion rate is desired, only one pass of the material is to be made, and close tolerances are to be maintained. Since the sharpness of the grain on the belt deteriorates, current control of the dimensional stability and frequent adjustment of the tool are required. Solid foam grinding wheels have been proposed, but they wear very quickly.

It is therefore an object of this invention to provide an abrasive brush tool which operates for an extended period of time with high dimensional stability and in particular opposes clogging of the abrasive brush tool by the abraded material.

SUMMARY OF THE INVENTION Accordingly, the present invention provides an abrasive brush tool, comprising (a) a plurality of brush bristles; (b) an embedded mass surrounding the bases of the brush bristles, but leaving free ends of the brush bristles non-embedded; and (c) abrasive grain bonded to the free, non-embedded ends of the brush bristles.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings, FIG. 1 is a plan view of an abrasive brush tool in accordance with the present invention;

FIG. 2 is a sectional view of the abrasive brush tool of FIG. 1, taken along line 2-2 of FIG. 1;

FIG. 3 is a broken away view on an enlarged scale in the region of the abrasive surface of the abrasive brush tool indicated by the letter A in FIG. 1; and

FIG. 4 is an illustration of the same broken away portion as in FIG. 3, but illustrating a further embodiment of the abrasive brush tool.

DETAILED DESCRIPTION The abrasive brush tool of the present invention is preferably in the form ofa circular (disc-shaped) brush for rotary abrasive use, the abrasive grain being arranged on the circumference of the circular brush. Preferably the wire bristles have a diameter ranging from about 0.3 to about 0.5 millimeters, and the diameter of the abrasive grain is about one-tenth of the diameter of the brush bristles.

Preferred grains for application to the free nonembedded ends of the brush bristles include boron carbide, silicon carbide and diamond.

The bond can be effected by an electrolytical precipitation. In this regard, it is feasible not only to precipitate a metallic bond, but also a cured resin (plastic) bond, by electrophoretic precipitation, which is known per se.

LII

Preferably, the abrasive brush tool has a diamond abrasive grain bonded with a metallic bond. The bristles are to good advantage embedded in foamed elastic material which is electrically non-conductive and indifferent to galvanic baths, the wire ends projecting from the mass. It has proven appropriate to have the wire ends project from the mass by 0.1 to 2.0 millimeters, in particular 0.2 to 0.5 millimeters. Preferably, the embedding mass is polyurethane, i.e. an isocyanatc resin formed by the reaction of a polyisocyanate, usually a diisocyanate, with a polyether or polyester.

In a preferred embodiment, a metallic coating is arranged between the free nonembedded ends of the brush bristles and the abrasive grain. This metallic coating preferably has a head-like form.

The abrasive brush tool of the invention can be made in a variety of different manners. According to one preferred method, the brush bristles are introduced into the embedding mass, whereby to form a blank body, as illustrated in FIGS. 1 and 2, i.e., a plurality of brush bristles in an embedding mass surrounding the bases of the brush bristles, but not having free nonembedded ends of the brush bristles. A layer of material is next ground off the surface of the blank body, whereby to expose the ends of the brush bristles, and a metallic coating is galvanically applied to the ends of the brush bristles exposed by the grinding operation. The metallic coating applied to the exposed end of the brush bristles is next lightly ground, and abrasive grain is applied galvanically to the lightly ground coating.

In another preferred embodiment, an elastic material is used for the embedding mass. After the brush bristles are introduced into the embedding mass, to form a blank body, the blank body is rotated at a rotational speed sufficient to stretch the embedding mass in the direction of the embedded brush bristles. A layer of the blank body is then ground off, whereby to expose the ends of the brush bristles and remove a portion of the embedding mass, while the blank body is being rotated. Rotation of the blank body is then discontinued, whereby to allow a relaxation and shrinking of the elastic material in a direction away from the free nonembedded ends of the brush bristles. In the case of an abrasive tool in the form of a circular brush for rotary abrasive use, the embedding mass is stretched in an outward radial direction, and relaxed in an inward radial direction. In the case where the abrasive tool is not in the form of a circular brush for rotary abrasive use, an appropriate arrangement can be made so that the stretching and relaxation occur in the proper directions.

After the elastic embedding material has shrunk away from the ends of the brush bristles, leaving them free and nonembedded, abrasive grain is applied to the projecting free nonembedded ends of the brush bristles. As indicated above, this can be either by metallic bonding or by means of a cured resin.

In the case of a circular brush for rotary abrasive use, the circumferential speed employed for radial stretching is preferably sufficient to cause a centrifugal force five times higher than that developed during ordinary operational speeds.

An advantage of this method of production of abrasive brush tools is that it permits production of slightly contoured wheels which are particularly suited for a later use for contour grinding, by the use of a contoured tool to cut both the brush bristles and the embedding mass in the same desired shape.

Another preferred method for the production of an abrasive brush tool in accordance with this invention comprises placing the brush bristles so as to intrude into a melted mass in a mold, cooling and solidifying the melted mass within the mold containing the intruding brush bristles, and filling the remaining space in the mold with plastic to form the embedding mass. In particular wax or paraffins are acceptable as melted masses, as they may be removed by heating again. Prior to the electrolytical application it is recommended to expose the free nonembedded ends of the brush bristles to solvent to free them from the adhering residue of the cooled solidified melt mass. Appropriately, the wire ends intrude into the melt mass from about 1 to about 2 millimeters.

If the abrasive brush tool is in the form of a circular brush for rotary abrasive use, the placement of the brush bristles so as to intrude into a melted mass in a mold is preferably accomplished by centrifuging.

The invention will now be explained in greater detail, with reference to the drawings.

Referring now to FIGS. 1 and 2, the brush bristles are denominated l, the embedding mass 2, the free nonembedded ends of the brush bristles (or simple wire ends) 3, and the abrasive grain particles which are bonded to the free, nonembedded ends of the brush bristles 4. FIGS. 1 and 2 show the circular brush in its unfinished state, although the brush circumference has already been ground circular. Electrically nonconductive material which is indifferent to galvanic baths may be used for the embedding mass 2, so that a coating by a galvanic procedure may be effected only on the ends 3 of the brush bristles. Foam embedding masses, in particularly based on polyurethane, are particularly well suited for use in the present invention.

FIG. 3 shows a broken away view on an enlarged scale in the region of the abrasive surface of the abrasive brush tool indicated by the letter A in FIG. 1. In FIG. 3, only the righthand part of the figure diagrammatically shows the final state of the abrasive tool,

while in the lefthand part of the FIG. 3 a specific manufacturing step is to be explained. According to one preferred method of producing the abrasive brush tools of this invention, head-like elements are built up on the ground off or slightly ground wire cross sections by a galvanic coating, which elements 5 represent and extension of the bursh bristles 1, beyond the circumference of the embedding mass 2. These elements 5 must again be ground to define a circular path of rotation, as indicated by reference 6, so that the application of abrasive grain 4 in the galvanic bath is affected uniformly and circularly. In the galvanic bath, the abrasive particles 4 are applied in a metallic bond to elements 5 in the required precision and strength.

In the embodiment illustrated in FIG. 4, galvanic ap plying of elements 5 and the subsequent circular grinding operation are not required. In this embodiment, application is effected in the galvanic bath directly onto the wire ends 3. In order to do so, it is necessary that in addition to the wire end exposed by lightly grinding, a portion of the wire bristles disposed further inwardly is exposed. Good results are obtained in practice if additionally 0.2 to 0.3 millimeters of the cylindrical portion of the end 3 of the brush bristles are available, as has been indicated diagrammatically in FIG. 4. Such an abrasive tool may be made from a blank according to FIG. 2, by selecting an elastic material as embedding mass 2 of the brush bristles 1, for the production of circular brushes, by reliably securing the brush bristles 1 against accidental detachment upon rotation and by then performing a circular grinding operation with very high rotational speeds. far in excess of those used in later operational use. Very good results are obtained with foam embedding material (with closed air pores), in particular polyurethane. With polyurethane alone, the resiliency may be determined in broad limits and with high precision by the mixing ratio of the components of the polyurethane. Since the grinding operation of the blank is performed with very high rotational speeds, the elastic embedding mass of the brush is stretched radially outward, and under these circumstances the embedding mass 2 of the wire ends 3 are ground to the same circumference, as indicated in FIGS. 1 and 2. In the subsequent stationary condition a shrinking of the embedding mass 2 occurs, and the ends of the brush bristles then project from the embedding mass. The application of elements 5 (special galvanizing operation) is unnecessary when using this procedure, as is the subsequent after-grinding operation of the heads so that this procedure is of particular advantage. It is furthermore pointed out that in using solid elastic embedding masses, the radial stretching of the embedding mass results in a transverse contraction with increasing wheel thickness during the high speed production circular grinding operation, at the location indicated in FIG. 2 by the arrows B. Therefore, for rolllike abrasive tools, having a long axis in relation to the diameter, a foam embedding mass is recommended in order to avoid this undesired form variation.

A particular advantage of the embodiment illustrated in FIG. 4 is the high self-cleaning effect of this abrasive tool. The reason for this may be considered to be that the abrasive surface has certain resiliency. The ends of the brush bristles 3 are more or less elastically clamped into the embedding mass 2. By the abrasion resistance, a pressure is exerted on the wire ends 3, and a certain recoiling is thereby caused. As soon as the abrasive engagement with the workpieces ceases, the wire ends 3 spring forward again and thus perform a relative movement regarding the tool upon each revolution, i.e., the wire ends oscillate or constantly swing. This causes a self-cleaning effect. For wide rolls the use of a scraper support is recommended. Such scraper supports are well-known in the prior art. They are among other embodiments known in the form of thick adhesive fabrics through which the wire scrapers are past from rearwardly. Such tools are, for instance, known as roughening tools in the shoemaker art. A solution proposed is to join such a conventional scraper support, possibly by a helical winding and a firm bonding by means of an adhesive, to a metal roll. The scrapers may then be provided with an abrasive grain coating, in the manner described above.

The abrasive tool of this invention is well suited for polishing operations or for aftergrinding operations on manually manipulating workpieces of the most complex shape. Thus, it has for instance proven that for wood workpieces of a complex form, the particularly cool abrasion of metallic bond with a weak application, and also for a grain too fine for the abrasive use up to now, satisfactory results can be obtained by increasing the pressure engagement, without a burning" being noted at the workpiece. For manual grinding operations, this brings about the advantage that in unintended contact between the tool and the workpiece does not result in damage which may mean retrimming operations or even scrap. Particularly for manual operations, the alignment of the workpiece into the proper grinding position is facilitated the more it may be brought into full engagement, before the actual grinding pressure is exerted. The abrasive tool of this invention is to be considered a tool dressed dull, in this greatly reduces the risks of injuries in practice when manipulating the tool manually. lnjuries by touching open abrasive belts are inevitable in practice, and are particularly painful. The abrasive tool of this invention therefore is of particular interest for the wood processing industries, since it does not bring about even visible traces in cases of contact with pressure engagement. A further advantage in the use will be noted in the sharpening of paper webs which are readily prone to burning. Proper and dimensionally true grinding operations have been achieved there with the abrasive tool of this invention.

I claim:

1. An abrasive brush tool, comprising:

a. a plurality of brush bristles;

b. an embedding mass surrounding the bases of the brush bristles, but leaving free ends of the brush bristles nonembedded; and

c. abrasive grain bonded to the free, nonembedded ends of the brush bristles.

2. An abrasive brush tool according to claim 1, in the form of a circular brush for rotary abrasive use, the abrasive grain being arranged on the circumference of the circular brush.

3. An abrasive brush tool according to claim 1, wherein the brush bristles have a diameter ranging from about 0.3 to about 0.5 millimeters.

4. An abrasive brush tool according to claim 1, wherein the diameter of the abrasive grain is approximately one-tenth of the diameter of the brush bristles.

5. An abrasive brush tool according to claim 1, wherein the brush bristles project from about 0.1 to about 2.0 millimeters past the end of the embedding mass.

6. An abrasive brush tool according to claim 1, wherein the brush bristles project from about 0.2 to about 0.5 millimeters past the end of the embedding mass.

7. An abrasive brush tool according to claim 1, wherein the embedding mass is electrically nonconductive and indifferent to galvanic baths.

8. An abrasive brush tool according to claim 1, wherein the embedding mass is polyurethane.

9. An abrasive brush tool according to claim 1, wherein the abrasive grains are bonded to the free nonembedded ends of the brush bristles by means of cured resin.

10. An abrasive brush tool according to claim 1, wherein the abrasive grains are bonded to the free nonembedded ends of the brush bristles by means of metallic bonding.

11. An abrasive brush tool according to claim 10, wherein the brush bristles are provided with metallic coating between the free nonembedded ends of the brush bristles and the abrasive grain.

12. An abrasive brush tool according to claim 1, wherein the grain is selected from the group consisting of boron carbide, silicon carbide and diamond abrasive grain.

13. An abrasive brush tool according to claim 1, wherein the abrasive grain is diamond which is metallically bonded to the free nonembedded ends of the brush bristles.

14. A process for producing the abrasive brush tool of claim 1, comprising the steps of a. introducing the brush bristles into the embedding mass, whereby to form a blank body;

b. grinding a layer off the surface of the blank body,

whereby to expose the ends of the brush bristles;

c. galvanically applying a metallic coating to the ends of the brush bristles exposed by the grinding operation;

cl. lightly grinding the metallic coating applied to the exposed ends of the brush bristles; and

e. galvanically applying abrasive grain to the lightly ground coating.

15. A process for producing an abrasive brush tool according to claim 1, comprising the steps of a. introducing the brush bristles into an embedded mass, the embedded mass being elastic material, whereby to form a blank body;

b. rotating the blank body at a rotational speed sufficient to stretch the embedding mass in the direction of the embedded brush bristles;

c. grinding off a layer of the blank body, whereby to expose ends of the brush bristles and remove a portion of the embedding mass;

d. discontinuing rotation of the blank body, whereby to allow a relaxation and shrinking of the elastic material in a direction away from the free nonembedded ends of the brush bristles; and

e. applying abrasive grain to the projecting free nonembedded ends of the brush bristles.

16. A process according to claim 15, wherein the abrasive tool is in the form of a circular brush for rotary abrasive use, and the embedding mass is stretched andd relaxed in radial directions.

17. A process for producing an abrasive brush tool according to claim 1, comprising the steps of:

a. placing the brush bristles so as to intrude into a melted mass in a mold;

b. cooling and solidifying the melted mass within the mold containing the intruding brush bristles;

c. filling the remaining space in the mold with plastic to form the embedding mass;

d. removing the cooled solidified melt mass, whereby to expose the free nonembedded ends of the brush bristles; and

e. applying abrasive grains to the free nonembedded ends of the brush bristles.

18. A process according to claim 17, wherein the abrasive brush tool is in the form of a circular brush for rotary abrasive use, and the placement of the brush bristles so as to intrude into a melted mass in a mold is accomplished by centrifuging.

19. A process according to claim 17, wherein the wire ends intrude into the melt mass from about l to about 2 millimeters.

20. A process according to claim 17, comprising in addition the step of exposing the free nonembedded ends of the brush bristles to solvent to free the ends of the brush bristles of adhering residue of the cooled so- 

1. AN abrasive brush tool, comprising: a. a plurality of brush bristles; b. an embedding mass surrounding the bases of the brush bristles, but leaving free ends of the brush bristles nonembedded; and c. abrasive grain bonded to the free, nonembedded ends of the brush bristles.
 2. An abrasive brush tool according to claim 1, in the form of a circular brush for rotary abrasive use, the abrasive grain being arranged on the circumference of the circular brush.
 3. An abrasive brush tool according to claim 1, wherein the brush bristles have a diameter ranging from about 0.3 to about 0.5 millimeters.
 4. An abrasive brush tool according to claim 1, wherein the diameter of the abrasive grain is approximately one-tenth of the diameter of the brush bristles.
 5. An abrasive brush tool according to claim 1, wherein the brush bristles project from about 0.1 to about 2.0 millimeters past the end of the embedding mass.
 6. An abrasive brush tool according to claim 1, wherein the brush bristles project from about 0.2 to about 0.5 millimeters past the end of the embedding mass.
 7. An abrasive brush tool according to claim 1, wherein the embedding mass is electrically nonconductive and indifferent to galvanic baths.
 8. An abrasive brush tool according to claim 1, wherein the embedding mass is polyurethane.
 9. An abrasive brush tool according to claim 1, wherein the abrasive grains are bonded to the free nonembedded ends of the brush bristles by means of cured resin.
 10. An abrasive brush tool according to claim 1, wherein the abrasive grains are bonded to the free nonembedded ends of the brush bristles by means of metallic bonding.
 11. An abrasive brush tool according to claim 10, wherein the brush bristles are provided with metallic coating between the free nonembedded ends of the brush bristles and the abrasive grain.
 12. An abrasive brush tool according to claim 1, wherein the grain is selected from the group consisting of boron carbide, silicon carbide and diamond abrasive grain.
 13. An abrasive brush tool according to claim 1, wherein the abrasive grain is diamond which is metallically bonded to the free nonembedded ends of the brush bristles.
 14. A process for producing the abrasive brush tool of claim 1, comprising the steps of a. introducing the brush bristles into the embedding mass, whereby to form a blank body; b. grinding a layer off the surface of the blank body, whereby to expose the ends of the brush bristles; c. galvanically applying a metallic coating to the ends of the brush bristles exposed by the grinding operation; d. lightly grinding the metallic coating applied to the exposed ends of the brush bristles; and e. galvanically applying abrasive grain to the lightly ground coating.
 15. A process for producing an abrasive brush tool according to claim 1, comprising the steps of a. introducing the brush bristles into an embedded mass, the embedded mass being elastic material, whereby to form a blank body; b. rotating the blank body at a rotational speed sufficient to stretch the embedding mass in the direction of the embedded brush bristles; c. grinding off a layer of the blank body, whereby to expose ends of the brush bristles and remove a portion of the embedding mass; d. discontinuing rotation of the blank body, whereby to allow a relaxation and shrinking of the elastic material in a direction away from the free nonembedded ends of the brush bristles; and e. applying abrasive grain to the projecting free nonembedded ends of the brush bristles.
 16. A process according to claim 15, wherein the abrasive tool is in the form of a circular brush for rotary abrasive use, and the embedding mass is stretched andd relaxed in radial directions.
 17. A process for producing an abrasive brush tool according to claim 1, comprising the steps of: a. placing the brush bristles so as to intrude into a melted mass in a mold; b. cooling and solidifyinG the melted mass within the mold containing the intruding brush bristles; c. filling the remaining space in the mold with plastic to form the embedding mass; d. removing the cooled solidified melt mass, whereby to expose the free nonembedded ends of the brush bristles; and e. applying abrasive grains to the free nonembedded ends of the brush bristles.
 18. A process according to claim 17, wherein the abrasive brush tool is in the form of a circular brush for rotary abrasive use, and the placement of the brush bristles so as to intrude into a melted mass in a mold is accomplished by centrifuging.
 19. A process according to claim 17, wherein the wire ends intrude into the melt mass from about 1 to about 2 millimeters.
 20. A process according to claim 17, comprising in addition the step of exposing the free nonembedded ends of the brush bristles to solvent to free the ends of the brush bristles of adhering residue of the cooled solidified melt mass. 